This revised continuation proposal builds upon ongoing research regarding vestibulo-ocular function in the elderly. The proposed research addresses, in part, priorities established in a Program Announcement entitled Mechanisms of Sensorimotor Adaptation issued jointly by the NIA and NASA. In particular, we will study the influence of aging on two well-described vestibulo~ocular reflex phenomena, velocity storage and visual-vestibular interaction. The latter studies will enable 1:10th eye movement assessments and a study of the influence of vestibular stimulation and visual suppression of the vestibulo-ocular reflex on cognitive processes. These studies are important because cognitive variables may play a critical role in vestibular processing, and because aging is associated with a decline in cognitive abilities, sensory capabilities, and vestibular function. Elderly subjects will be drawn from a pool of healthy community- dwelling individuals between the ages of 65 and 75. Control subjects will be healthy individuals aged 20 to 30. Vestibular stimulation will consist of earth-vertical axis and off-vertical axis rotation. Eye movements will be recorded with the magnetic scleral search coil technique and with electro-oculography. Cognitive tasks will consist of simple and complex reaction time measures using auditory cues. Subjects will perform these tasks during vestibular stimulation, visual-vestibular interaction, and several control conditions. All three aspects of the proposed study, namely, velocity storage, visual-vestibular interaction, and the influence of vestibular stimulation and visual suppression of the vestibulo-ocular reflex on cognitive performance depend upon multi-neuronal pathways and will allow an improved understanding of how aging affects the balance system, specifically, the processing of vestibular signals by the CNS.